Tag Archives: iis

Debugging locally REST API webhooks with Visual Studio

Modern REST APIs such as Outlook REST Api, Microsoft Graph or Facebook Graph expose very powerful capabilities called webhooks. They allow push notifications. After subscription, when something change these API send notifications to your service by calling the URL you provided. For example, in Outlook REST API the push notification services will send a request when something has been modify in the user mailbox such as a mail received or an email marked as read.

I am not going to explain how you register subscriptions to a particular webhook. In this blog post, we provide a solution in order to be able to “break” with your Visual Studio debugger in a callback webhook you subscribed to. The approach is not windows/.NET specific, actually the mechanism exposed here is generic, but these are the tools I am using at the moment so they will serve as example in this post.

Problem: when you subscribe to a webhook you specify what would be your notification URL (see Outlook REST API example). This url must be https and visible from the ‘outside’ internet. Therefore, you cannot set an url such as https://localhost:44301/api/MyNotificationCallBack where https://localhost:44301 is the url of your local development website.  However, it would be convenient in order to ‘break’ directly in your server side code responsible for handling the request. In addition, if you are using Visual Studio and IIS express for development you cannot simply expose a website with custom domain and SSL to the outside internet.

Solution: take a (sub)domain name you own (e.g. superdebug.keluro.com) then create an A record to point to your public IP. If you are in a home network this IP is the one of your ISP box. Configure this box to redirect incoming traffic for superdebug.keluro.com on port 443 to your personal developer machine (still on port 443). In your machine, configure an IIS web server with a binding for https://superdebug.keluro.com on port 443 that will act as reverse proxy and will redirect incoming traffic to your IIS Express local development server  (e.g. https://localhost:44301). Finally, set a valid SSL certificate on the reverse proxy IIS server for superdebug.keluro.com. Now, you can now use https://superdebug.keluro.com/api/MyNotificationCallBack as notification Url and the routing logic will redirect incoming push notification requests to https://localhost:44301/api/MyNotificationCallBack where you can debug locally.

Debug IIS Express website visible from the outside internet

Debug locally IIS Express website visible from the outside internet


  • Unfortunately, in case of home network, I cannot give precise instructions on how to configure your ISP box to reroute incoming traffic. Also make sure that the box IP does not change and is static.
  • Take care of your own Firewall rules, make sure that 443 port is open for both Inbound and Outbound rules.
  • In IIS Application Request Routing (ARR), the module that may be used for creating the reverse proxy, an option is set by default that modifies ‘location’ request response Headers. It may break your application that probably uses OAUTH flow. See this stackoverflow response.
  • If you never setup IIS to work as a reverse proxy. That is quite simple now with ARR or Rewrite Request modules. In this previous blog post we explained how to setup a reverse proxy with IIS.

TeamCity on Windows Azure VM part 2/2 – enabling SSL with reverse proxy

In the previous post we explained how to install a TeamCity server on a Windows Azure Virtual Machine. We used an external SQL Azure database for the internal database used by Teamcity. The first post ended with a functional TeamCity web app that could not be visible from outside. The objective of this second post is to show how to secure the web app by serving up the pages with SSL. Similarly as the previous post I will detailed out all the procedure from scratch so this tutorial will be accessible to an IIS beginner. Indeed, we are going to use a reverse proxy technique on IIS (Internet Information Service, the Microsoft web server).  I would like to thank my friend Gabriel Boya who suggested me the reverse proxy trick. Let us remark that it could also be a good solution for serving under SSL any other non IIS website running on windows.

If you have followed the steps of the previous post, then you should have a TeamCity server that is served on port 8080. You should be able to view it with the IE browser under the remote desktop VM at localhost:8080. Let us start this post by answering the following question:

What is a reverse proxy and why use it?

If you try to enable SSL with Tomcat server who serves TeamCity, you are going to suffer for not a very good result. See for instance this tutorial and all the questions it brought. Even if you manage to import your certificate on the java certificate store, you will have problem with WebSockets…

So I suggest you to implement a reverse proxy. The name sounds complicated but it is very basic concept: this is simply another website that will act as an intermediate for communicating to your first and primary website (in our case the Tomcat server). Here, we are going to create an empty IIS website, visible from outside on port 80 and 443. It will redirect the incoming request to our TeamCity server which is listening on port 8080.

Representation of the reverse proxy for our situation

Representation of the reverse proxy for our situation

Install IIS and the required components

First we will have to install and setup IIS with the following features on our Windows server 2012. It is a very easy thing to do. Search the ServerManager in windows  then, choose to configure this Local Server (this Virtual Machine)  with a Role-based installation.


Add roles and features

Then, check the “Web Server (IIS)” as a role to install.


Install IIS

Keep the default feaures.


Keep default installation features

In this recent version, TeamCity uses the WebSockets. To make them work, our reverse proxy server will need them: check WebSocket Protocol.


Check the WebSocket Protocol

Check that everything is right there… and press Install.


Check that everything is prepared for installation

Now that we have installed IIS with our required features (WebSocket),it is accessible from the menu. I suggest you pin that to the easy launch if you do not want to search it each time you will need it.


IIS well installed

Install URL rewrite module

The most simple way to set up the reverse proxy is to have the IIS URL rewrite module installed. Any Microsoft web modules should be installed using the Microsoft Web platform Installer. If you do not have it yet, install it from there.

Then, in the Web Platform Installer look for the URL Rewrite 2.0 and install it.


URL Rewrite 2.0 installation with Web Platform Installer

The Reverse proxy website

Ok now we are going to create our proxy website. IIS has gently created a website and its associated pool. Delete them both without any mercy and create a new one (called TeamcityFrom) with the following parameters. Remark: that there is no website and nothing under the C:inetpubwwwroot this is just the default IIS website directory.


New TeamCityFront IIS website that point to the inetpub/wwwroot folder

Create the rewrite rule

We are going to create a rule that basically transform all incoming http request to request targeting locally localhost:8080. Open the URL rewrite menu that should be visible in the window when you click on your site and create a blank rule with the following parameters.


URL Rewrite for our TeamcityFront website


second part of the rewrite rule

Now let us go back to the management Azure portal and add two new endpoints http for port 80 and https for 443 in Windows Azure


Add HTTP on port 80 and HTTPS on port 443 with the Azure Management Portal for our VM

Now check that you are able to browse your site at testteamcity.cloudapp.net from the outside. But you could object what was the point? Indeed, we could have setup TeamCity on port 80 and add the HTTP endpoint on Azure and the result would be the same. Yes you would be right, but remember, our goal is to serve securely with SSL!

Enabling SSL


Certificate installation

To enable SSL you need to have a certificate, you can buy one at Gandi.net for example. When you get the .pfx file install it on your VM by double clicking and put the certificate on the personal store.

An SSL certificate is bound to a domain and you do not own cloudapp.net so you cannot use the subdomain testteamcity.cloudapp.net of your VM. You will have to create an alias for example build.keluro.com and create a CNAME that will redirect to the VM.

Here is the procedure if you manage your domains in Office365.


Creating a CNAME subdomain in Office365 that point to the *.cloudapp.net address of your VM

Now in IIS, click on your site and edit SSL bindings, add this newly created  subdomain build.keluro.com and use the SSL certificate that should be recognized automatically by IIS.


Create an HTTPS binding for the proxy server under IIS

At this stage, you should be able to browse your site on https from the outside with a clean green lock sign.

Browsing in security with https

Browsing in security with https

Redirection Http to Https

You do not want your user to continue accessing insecurely your web app with basic Http. So a good mandatory practice is to redirect your http traffic to a secure https endpoint. Once again, we will benefit from the reverse proxy on IIS. Simply create a new URL rewrite rule.


An HTTP to HTTPS redirect rewrite rule

Then place you HTTPS redirection rule before the ReverseProxy rule.


Place the HTTPS redirection rule before the ReverseProxy rewrite rule

Then know when you type http://build.keluro.com or simply build.keluro.com you’ll be automatically redirected and the job is done!


A working website that redirects automatically to https